Ball bearing manufacturing method



Feb. 27, 1968 c. D.G1BSON BALL BEARING MANUFACTURING METHOD 7Sheets-$heet 1 Original Filed Oct. 19, 1964 Feb. 27, 1968 c. D. GIBSON3,370,333

BALL BEARING MANUFACTURING METHOD Original Filed Oct. 19, 1964 7Sheets-Sheet 2 I C. D. GIBSON Feb. 27, 1968 BALL BEARING MANUFACTURINGMETHOD 7 Sheets-Sheet 5 Original Filed Oct. 19, 1964 FIG. 3

C. D. GIBSON BALL BEARING MANUFACTURING METHOD Feb. 27, 1968 OriginalFiled Oct. 19, 1964 Feb. 27, 1968 c. D. GIBSON 3,370,333

BALL BEARING MANUFACTURING METHOD Original Filed Oct; 19, 1964 '7Sheets-Sheet 5 Feb. 27, 1968 c. D. GIBSON BALL BEARING MANUFACTURINGMETHOD Ori inal Filed Oct. 19, 1954 Feb. 27, 1968 c. D. GIBSON 3,370,333

BALL BEARING MANUFACTURING METHOD Original Filed Oct. 19, 1964 '7Sheets-Sheet 7 iiinii ii i,

United States Patent Ofiice 3,370,333 Patented Feb. 27, 1968 BALLBEARING MANUFACTURING METHOD Christian D. Gibson, Greene, N.Y., assignorto The Raymond Corporation, Greene, N.Y., a corporation of New YorkOriginal application Oct. 19, 1964, Ser. No. 404,988, now Patent No.3,332,728, dated July 25, 1967. Divided and this application June 12,1967, Ser. No. 645,104

5 Claims. (Cl. 29-1484) ABSTRACT OF Tl-E DISCLOSURE Method ofmanufacturing a ball-bearing by forcing sets of hardened racewirestogether on a set of balls while rotating the racewires, to cold-workthe corners of the racewires to provide bearing seats arcuate incross-section. A number of industrial applications, many of which relateto material-handling apparatus, require the use of large diameter ballbearings capable of rotatably carrying massive loads.

This invention relates to improved ball bearings and to a method formanufacturing same, and is a division of my prior copending appl. Ser.No. 404,988 filed Oct. 19, 1964, now Patent No. 3,332,728.

It is a well known fact that steel rings distort when hardened, which isthe principal reason why the rings of anti-friction bearings must beground after hardening if accurate running is to be achieved. The costof grinding, however, rises so steeply with increase in hearing ringdiameter that it is usually uneconomical to use precision-type lowfriction hearings in large diameters, and thus many applicationsrequiring large diameters have utilized plain sliding bearings, despitethe clear advantages of anti-friction bearings.

The undesirable eiiects of hardening the rings can be avoided either byusing unhardened races, or by separating the races from the ringsenclosing them. However, a bearing with unhardened races has arestricted loadcarrying capacity, so that track indentations frequentlyoccur even under light loading, giving rise to noisy and jerky runningof the bearing, and strong shock loads frequently ruin such bearings.Bearings with unhardened races can only be economically employed if thediameter of the bearing is suificiently large to permit a low specificloading. A number of bearing applications, such as bearing mountings forsteerable traction assemblies in compact lift trucks, preclude the useof low specific loadings, due to the heavy loads carried by such trucksand the space limitations.

Because of the above difliculties, the bearing provided by the presentinvention, rather than using unhardened races, provides hardened steelwire inserts within unhardened supporting rings. When assembled, thehardened wire inserts are pressed tightly against the enclosing,unhardened supporting rings, so that the latter are ultimatelyresponsible for accurate running of the bearing.

The use of hardened steel wire inserts to form largediameter ballbearings is known to the prior art. However, the various forms ofwire-race ball bearings known in the prior art are unsuitable forcertain applications where particular types of loading are encountered.In general, wire-race ball bearings of the prior art have been suitablefor applications involving largely radial loading and little axialloading, and applications involving radial loading and axial loading ofapproximately the same amounts, but no suitable wire-race ball bearingshave been available for applications which principally involve axialloading and relatively little radial loading. Many lift truckapplications involve extremely heavy vertical loads due to the heavyloads handled by such trucks, and such vertical loads act axially on abearing used to support a steerable tractive or drive assembly. Theradial loads on such bearings are considerably smaller, however, as theydepend more upon the tractive and braking thrusts applied to propel thetruck than upon the weight of the heavy load carried by the truck. Asthe truck turns, the inertia of the load carried by the truck does applysome radial load to the drive assembly bearing, but the speeds andturning rates to which such trucks are limited in order to avoidoverturning automatically limit such additional radial loads, so thatradial loading is usually slight compared to axial loading, and seldomif ever approaches the magnitude of axial loading. Prior art wire-racebearings designed for principally radial loading, or approximately equalamounts of radial and axial loading, are subject to undue wear when usedin some applications, such as the lift truck application mentioned,wherein loading is principally axial. The present invention provides anew form of wire-race ball bearings especially adapted to carryprincipally axial loads. Thus it is one object of the present inventionto provide a method for manufacturing an improved wire-race ball bearingadapted to carry principally axial loads.

Using prior art wire-race bearings, where various combinations of radialloading, axial loading and tilting moments have been encountered,various attempts have been made to accommodate various combinations ofloading by provision of plural bearing assemblies. It is another objectof the present invention to provide a wirerace bearing assembly capableof carrying the heavy axial loads mentioned with a single assembly.

In the prior art, wire-race ball bearings have been formed bycold-working wire-races of circular cross-section to provideinwardly-extending surfaces of arcuate cross-section, by applyinggreater than normal load forces to an assembled bearing assembly, androtating the assembly until the balls within the assembly forminwardlyextending tracks of arcuate cross-section in the wire of acircular cross-section. While hardened steel wires of both circular andrectangular cross-section have been used as insertable wire races, thoseof rectangular cross-section heretofore have been used in rollerbearings rather than ball bearings. Wire race roller bearings, however,like most other types of roller bearings, are completely incapable oftaking appreciable axial loads and are not intended to take axial loads.While the prior art has utilized wire races of circular cross-sectionfor ball bearings, the present invention contemplates the use instead ofnoncircular or rectangular wire races, since it is much easier toprovide rectangular recesse in the unhardened steel rings surroundingthe Wire recesses, and rectangular recesses much better fix the races inplace and better support the races, much improving the accuracy and thelife of the bearing.

While the exact reason may not be certain, it appears that serious wearof wire race bearings occurs, at least sometimes, if the wire races arenot held fixedly against the unhardened bearing rings. In prior art wirerace ball bearings wherein circular wire races have been employed, it ispossible for portions of each circular wire to rotate at least slightlyabout its own longitudinal axis, and such rotation sometimes may developforces tending to urge portions of a wire race away from the unhardenedsupporting ring against which it should fixedly seat. By usingnon-circular wire races seated in non-circular recesses in theunhardened supporting rings, rotation of the wireraces about their ownlongitudinal axes is minimized. It also appears that rotation of thewire races is affected by the placement of the wire races around theball. If four wire races are equally spaced around the balls ninetydegrees apart, a given amount of axial or thrust loading :appears toapply somewhat greater twisting moments tending to rotate the wiresabout their own axes than if the wires are spaced around the ball in themodified configuration used in the invention. Thus a further object ofthe invention is to provide an improved wire race ball bearing in whichrotation of the race wires about their own axes is minimized.

When hardened steel wires of circular cross-section have been utilizedin the prior art, a flat surface has been ground along the length of thecircular wires prior to running-in the bearin g assembly, in order thatthe hardened steel Wires present an initially flat surface rather than arounded surface to the balls, and then as the bearing assembly isrun-in, the balls form a track or groove of arcuate cross-section in theflat surface, pro viding line contact rather than point contact betweenball and race in the finished hearing. In 'order that the :arcuategroove have uniform depth along its entire length, it has been necessarythat the flat surface be ground on the hardened steel wire verycarefully and uniformly, which is time-consuming and expensive. Inaccordance with one method of the present invention, the wire-races ofrectangular cross-section are not pre-ground, but instead a corner ofeach race wire is presented to the balls, and as the assembly is run-in,the metal forming the corner of each race wire is cold-worked to providetracks of arcuate cross-section. While it might appear initially thatthis method of the present invention is preferable to that of the priorart only in that it eliminates the timeconsuming grinding operation, itwill become evident upon reflection that r unningin such an assembly totransform a corner to a groove of arcuate cross-section results inconsiderably more movement of metal than provision of a groove ofequivalent depth in a pre-ground flat surface, and because suchadditional cold-working serves to further harden the wire races, thismethod of the present i vention provides superior bearings which areless subject to wear.

However, in many bearing assemblies according to the present invention,the wire races will not require the extra hardening that such extrametal movement provides, and the bearing assemblies will be run-in byinitially presenting an almost tangential bearing surface 'of eachnon-circular race wire to the balls. Using rectangular race wire, itwill be seen that no time-consuming pregrinding such as that done in theprior art is necessary.

Thus it is a further object of the invention to provide an improvedmethod for manufacturing wire-race bearing assemblies.

It is desirable that the balls used in large diameter hearing assembliesbe removable. Various prior art bearing assemblies using insertableraces have required complete dismantling in order for the balls to beremoved and re placed, and other prior art assemblies have employedouter supporting rings which have been split to allow the rings to beexpandable, by means of a crow-bar or the like, to spring the ringssufficiently to allow the balls to be removed. Because the supportingring itself ultimately determines the roundness of the bearing, forciblyex: panding the supporting ring to a non-circular shape to allow ballremoval is very undesirable, since one cannot be certain that thesupporting ring will return to a precisely circular shape. Furthermore,providing a split through a supporting ring obviously weakens the ringat its split portion, or alternatively requires additional means forstrengthening the split portion. In accordance with the presentinvention, the bearing supporting rings are not split, but are rathercontinuous. and ball removal and replacement is accomplished withoutdeforming such supporting rings in any way. Thus it is a further objectof the invention to provide an improved wire-race bearing of the typedescribed in which ball removal and replacement is easily accomplished.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the several steps and the relationor one or more of such steps with respect to each of the others, and thearticle possessing the features, properties, and the relation ofelements, which are exemplified in the following detailed disclosure,and the scope of the invention will be indicated in the claims. For afuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawings, in which:

FIG. 1 is a cross-section view of a portion of a known prior artwire-race bearing assembly.

FIG. 2 is a comparable cross-section View through a portion of awire-race bearing assembly constructed in accordance with the presentinvention;

FIG. 2a is a cross-section view through an alternate wire race bearingassembly of the present invention;

FIG. 3 is a top view, with certain parts cut away, of one form ofbearing assembly constructed in accordance with the invention;

PEG. 4 is an exploded view of the assembly shown in FIG. 3;

FIG. 5 is a view taken downwardly along lines 5-5 in FIG. 2 and FIG. 6is a view taken downwardly along lines 6-6 in FIG. 2, with FIGS. 5 and 6also illustrating an arrangement provided for access to the hearingassembly for removal and replacement of balls;

FIG. 7 is a view taken along lines 77 of FIG. 5;

FIG. 8 is a view taken along lines 88 'of FIG. 5;

FIG. 9 is an elevation view, with certain parts shown in cross-section,illustrating apparatus which may be used in practicing the method of theinvention;

FIG. 10 is a top view of a portion of the apparatus of FIG. 9, takenalong lines 10-10 of FIG. 9, with certain parts shown partially cutaway; and

FIG. 11 is a cross-section view taken along lines 11-11 in FIG. 10.

In FIG. 1, a cross-section view showing the prior art wire-race bearingassembly, circular rotatable member 10 having a radiallyinwardly-extending annular recess 12 is subject to a heavy axial load P.Moment loads applied to the bearing will be seen to result in combinedaxial and radial loads. Stationary supporting ring member 14 is providedwith a radially outwardly-extending recess 16. A clearance gap of widths exists between the outer face of inner ring member 10 and the innerface of outer ring member 14. The recesses 12, 16 of members 10 and 14circularly extend around members 10 and 14, but members 10 and 14 areotherwise often very non-circular, and may comprise complex-shapedcastings in various applications. Four hardened steel race wires 14 aresituated in recesses 12 and 16 as shown, and extend completely aroundsuch recesses, except for small gaps (not shown) where the two ends ofeach race wire meet. A plurality of hardened balls, such as balls 20 and21 are laced between the race wires as shown, thereby rotatablysupporting movable member 10 with respect to stationary member 14. Asshown in FIG. 1, each race wire has a generally circular cross-section,except for a seat of armate cross-section which conforms to the radiusof the balls 20, 21. As mentioned above, such arcuate seats have beenprovided in the prior art along the lengths of circular race wires 1-4first by grinding flat surfaces along the lengths of wires 14, and thenby running-in the bearing assembly with a greater-than-normal load.

With an axial load force P applied to rotatable member 10, race wire 2will be seen to be urged downwardly against each ball with a force ofP/N, where N equals the number of balls provided around the bearing.Each ball will be seen to engage race wire 2 along a small arc, and theP/]\' force at each ball will be distributed along such an arc. Theresultant force applied to each ball acts through the center of the balland is applied to wire race 3 carried on stationary member 14, whichwire race each ball engages throughout a similar small arc. It will beseen that with the arrangement shown, the pure downl 1 ward axial load Pis transmitted radially as well as axially, with a radial componentequal to the axial component in the arrangement shown, so that theresultant forces between race wires 2 and 3 and the balls areconsiderably greater than the vertical load. In FIG. 1, wherein racewires 2 and 3 are 'equally spaced at 90 degrees around each ball, theresultant force across each ball is equal to Ncosu where a is the anglebetween vertical force P and a line connecting the centers of race wires2 and 3, the angle a being 45 degrees in the prior art assembly ofFIG. 1. Thus because the balls resolve axial loads into combined radialand axial loads, the resultant forces between the balls and the racewires are considerably increased. With the arrangement shown in FIG. 1,with the four circular race wires spaced ninety degrees apart aroundeach ball, the resultant force is 41.4% greater than the axial forceitself. The application of such increased forces to the balls obviouslyrequires the use of larger diameter hearing assemblies, or the use ofharder races and balls, or is results in bearing wear.

In the bearing assembly of the present invention shown in FIG. 2, theresultant forces which axial loads apply to the balls are substantiallyreduced, allowing much heavier axial loads to be imposed upon thebearing assembly. As shown in cross-section in FIG. 2, the bearingassembly of the present invention includes as before, four hardenedsteel wire race wires, labelled 31-34 in FIG. 2, but also a pair ofhardened steel side rings 37 and 38. It is important to note that whilerace wire 32 is located diametrically across each ball from race wire33, just as race wire 2 was diametrically across from race wire 3 in theprior art, that race wires 3134 are not equally spaced at 90 degreeintervals around the balls. Instead the arcuate seats of race wires 31and 32 are spaced much more closely together than 90 degrees, race wires33 and 34 are spaced together much more closely than 90 degrees, racewires 31 and 33 are spaced apart much more than 90 degrees, and racewires 32 and 34 are also spaced apart much more than 90 degrees. Such anarrangement allows the angle a to be markedly decreased, with the resultthat axial loads of greater magnitudes can be applied to the bearingassembly. The arrangement shown also applies smaller turning moments tothe race wires, so that there is less tendency for the race wires totwist about their own axes.

As will be evident from FIG. 2, upper race wires 31, 32 and lower racewires 33, 34 are each provided with arcuate seats. As in the prior art,such seats are provided by running-in a bearing assembly undergreater-thannormal loading in order to cold-work the bearing races, butas will be explained below, the method of the present invention issomewhat difierent from that of the prior art. It may be noted that noarcuate seats are provided in side race wires or bands 37 and 38.

In FIG. 2, the angular distance measured around the ball between centersof the arcuate seats of race pairs 31, 32 and 33, 34 is reduced toapproximately 30 degrees, rather than 90 degrees as in the prior art,and correspondingly, the angular distance between centers of the arcuateseats of race pairs 31, 33 and 32, 34 is increased to approximately 150degrees, rather than the 90 degree spacing of the prior art. With suchmodified spacing, the angle a is decreased to degrees, and l/cos 15equalling approximately 1.035, it will be see-n that the resultantforces which an axial load now will apply to the balls will be reducedfrom 41.4% more than the axial force, to merely 3.5% more than the axialforce, drastically increasing the axial loa -handling capability of thebearing.

A typical complete wire race ball bearing assembly constructed inaccordance with the present invention is illustrated in FIGS. 3 and 4,wherein a rotatably mounted lift truck steerable drive assembly bearingis shown. Shown partially cutaway in FIG. 3, is an outer casting 14which is provided with a plurality of mounting holes 15, 15 to allow itto be fixed to other structures such as the base frame of a lift truck.Outer casting 14, which need not be hardened, is provided with a largecircular bore and serves as the outer supporting ring of the bearingassembly. Concent-rically situated within the circular bore of outersupporting ring 14 is circular casting 10, also unhardened, which servesas the inner supporting ring of the bearing assembly. A large number ofballs 20, 20 are spaced between relatively-rotatable members 10 and 14,and in FIG. 3 the balls are shown partially obscured by upper race wires31 and 32. The diameters of the inner and outer castings are selectedwith respect to the diameter of the balls so that an integral number ofballs extend around the bearing, with a very small amount of free spaceusually less than one ball diameter. At one point around the peripheryof outer mounting ring 14 an access opening containing removable accessplug 40 is provided.

Shown mounted on inner member 10 is motor M and gear box G. Gearbox Gextends downwardly through an opening in member 10 to connect to a truckdrive wheel (not shown). Because the truck carries extremely heavyloads, heavy axial loading is applied to the bearing assembly, tendingto move outer member 14 downwardly with respect to inner member 10. Itwill be recognized that application of the improved bearing assembly toa lift truck steerable drive assembly is exemplary only, and that theinvention is applicable to a variety of other industrial applicationswhere bearings are subjected to principally axial loading.

As shown in FIG. 2, outer supporting ring 14 is provided with a recesshaving a first portion which accommodates outer race wires 31 and 33,and a second portion extending further radially outward to accommodateside race wire or band 37. It will become apparent that it is notnecessary to provide a recess having exactly the cross-section shown.However, it is important that the cross-section of the recess include atleast two portions of non-circular cross-section to accommodatenon-circular upper and lower race wires 31, 33, and a fiat surfaceportion to support side race wire 37. Similarly, the crosssection of theradially inwardly-extending recess in inner supporting ring member 10should include at least two corners or non-circular portions toaccommodate noncircular race wires 32 and 34, and a fiat portion tosupport race wire 38. The two recesses in members 10 and 14 and theintermediate space between them is termed the raceway of the bearing.

Race wires 31-34 and 37, 38 are formed from hardened high-grade springsteel, which is resilient in order that the race wires conform to thesurfaces of the grooves in inner and outer supporting ring members 10and 14, and which is hardened to provide bearing strength. The hardnessof typical race wires is 35-50 Rockwell C scale, and balls 20, 21, etc.generally have a hardness of about 60 70 Rockwell C. Inner and outerring supporting members 10 and 14 need not have bearing hardness, ofcourse, and ordinarily they are much softer in order that they be easilymachinable.

Some embodiments of the invention may find it advantageous to includerace wires having dilferent contact areas, such as the race wireconfiguration shown in FIG. 2a, wherein upper race wire 32' on innerring member 10 and lower race wire 33' on outer ring member 14, whichtwo race wires normally carry the axial load, are provided with widerarcuate contact surfaces than race wires 31' and 341, since the latterare much less subject to loading.

Upper and lower inner race wires 32 and 34 are formed around a mandrel(not shown) having a slightly smaller diameter than that portion of therecess against which these races wires are installed, so that race wires32 and 34 .assume a free shape such as shown in FIG. 4, wherein theirends overlap, and when these rings are expanded and installed on innermember 10, they resiliently grip member 10. When installed on member 10,the ends of wires 32 and 34 do not overlap, and to the contrary, thelengths of wires 32 and 34 are selected so that a small gap (of theorder of inch in a 12 bearing) remains between the ends of each racewire to allow for heat expansion. Race wires 32 and 34 preferably arealso bonded in position on member 10 to prevent the scrubbing forcesapplied to them by the balls from moving them around the raceway. Likewires 32 and 34, inner radial race band 38 is formed with a slightlyundersize radius and then expanded when installed so as to resilientlygrip inner ring member 10. Band 33 is also preferably bonded.

Upper and lower outer race wires 31 and 33 are formed around a mandrelhaving a slightly larger diameter than the recess surfaces against whichthese race wires bear, so that these wires assume an expanded free shapeas shown in FIG. 4, with a large gap between the ends of each of thesetwo race wires. When wires 31 and 33 are inserted into the recess inouter member 14, they are compressed, so that their spring force tendsto hold them tightly in place within the recess. Similarly, outer radialrace band 37 is formed with a slightly oversize radius, and thencompressed into place in the recess within outer ring member 14. Thelength of race band 37 is chosen so that a gap slightly wider than thediameter of a ball remains between the ends of band 37 when it iscompressed into place. As will be explained below, this gap between theends of band 37 is substantially bridged by a removable access plug whenthe bearing is assembled, so that a surface which is substantiallycontinuous around the entire raceway is provided to receive radialforces from the balls.

The angular positions around member 10 of inner race wires 32, 34 and 38is unimportant, although it is desirable to stagger the joints betweenthe ends of these three wires to three separate locations around member10. The angular positions of outer race Wires 31, 33 and 37 isimportant, however, and as will be explained, the ends of each of theserace wires are fixedly located adjacent the access hole through whichballs are removed and replaced.

The arrangement of the hardened race wires within the recesses ofsupporting ring members 10 and 14, and the details of the accessarrangement to allow ball removal will be clear from reference to FIGS.8. A circular bore hole is provided through outer ring member 14 toaccommodate a removable circular access plug 40, which is held in placeby bolts 43 (and washers 44), with the head of plug 40 seated against anenlarged diameter portion of the bore to determine the inward extensionof plug 40. The length of plug 40 is established to locate the face ofthe inner end of plug 40 at the same radial position as the inner faceof outer side race wire 37, and therefore, the balls are continued to besupported radially and are prevented from moving radially outwardly tocatch in the access bore as they pass the access bore. If desired, theface of plug 40 may be slightly hollowedto a radius of curvaturecorresponding to that of the inner face of the side race wire 37, butthen it is necessary that plug 40 be inserted at a proper angularposition about its own axis. Marks may be placed on plug 40 and housing14 to insure that plug 40 is properly oriented.

As best seen in the outward view shown in FIG. 8, the ends of outer racewires 31 and 33 are chamfered to provide a slightly increased verticalspacing or separation distance between these wires at their endsdirectly adjacent and across the access hole containing access plug 40,so that neither race wire covers any portion of the access hole, therebyallowing a ball which registers with the access hole to be removed whenaccess plug 40 has been removed.

Each end of both outer race wires 31 and 33 is partly chamfered andpartly squared. Upper and lower locating pins 41 and 42 are force-fittedinto holes above and below plug 40 to extend a short distance into theraceway, as best shown in FIG. 7. The squared portions of the ends ofouter race Wires 31 and 33 butt against the inner ends of pins 31 and33,and hence outer race wires 31 and 33 are restrained againstappreciable movement around the raceway, thereby insuring that thechamfered ends of race wires 31 and 33 remain adjacent the access bore,which is necessary for ball removal. Movement of inner race wires 32, 34and 38 around the raceway does not interfere, of course, with ballremoval, and hence it is unnecessary to positively restrain suchmovement by means of pins or the like.

Apparatus for running-in the upper and lower race wires for a wire-racebearing assembly is shown and described in connection with FIGS. 9-11.As mentioned above, the wire races previously used for ball bearingassemblies have been circular in cross-section, and the arcuate seats ortracks in such races have been run in first by grinding a flat surfaceon such wires, and then applying greater-than-normal load forces to sucha bearing in order to deform it by cold-working to provide the tracks ofarcuate cross-section along the lengths of the races. In accordance withthe present invention, wires of rectangular, or at least non-circularcross-section are provided and no grinding operation is necessary.Furthermore, preparatory to the races being run-in to provide the tracksof arcuate cross-section, the rectangular wireraces are fixed in a jigso as to present a corner rather than a fiat surface to the balls usedin the running-in process.

FIG. 9 shows a drill-press type of arrangement for running-in wireraces. In accordance with the present invention, four wire racesintended to be used as wires 3134 of a bearing assembly are run-intogether, and thereafter treated as a matched set. In FIG. 9 stationarywork table 51 carries a lower platen 63 comprising a circular platehaving a circular recess 54 which extends completely around the platen53, lower platen 53 being fixedly bolted to work table 51, by means ofbolts such as 55. An upwardly-extending central axle 52 is journalled inthe center of lower platen 53 to rotatably support upper platen 60.Recess 54, as better seen in the enlarged view of FIG. 11, is providedwith two bottom recesses 56 and 57, into which race wires of appropriatelength to form lower race wires 33 and 34 are situated. Thrust bearing63 is mounted in lower platen 53 to serve as a vertical stop to maintaina predetermined minimum distance between platens 53 and 60. Wiresdestined to form upper race wires 31 and 32 are similarly located inupper platen 60, in recesses 58 and 59, as best seen in FIG. 11.

Upper platen 60 is provided with an upwardly extending shaft 61 arrangedcoaxially with axle 52, and shaft 61 is connected by flexible coupling62 to shaft 65. Shaft 65 is connected to be rotated by rigid coupling64, which in some embodiments of the invention may take the form of adrill chuck. Coupling 64 is both rotated and reciprocated vertically byhollow shaft 66, which is supported for vertical movement by drill pressframe 67.

As best seen in FIG. 10 the wire races are run-in using a limited numberof balls 20 (four being shown in FIG. 10), wherein a portion of upperplaten 60 is cutaway). During the run-in process, the four balls aremaintained degrees apart by means of arcuate spacer bars 71, 71preferably formed of a soft metal such as brass.

der-piston assembly 70. When running-in has progressed to a point wherethrust bearing 59 prevents further travel of upper platen 60, the racewires within upper and lower platens 53 and 60 will be cratered to aproper depth. A plurality of holes 72, 72 are provided in upper platen60 to admit a punch to aid in removal of the cratered wires from upperplaten 60.

As the running-in process begins, all four race wires initially presentrectangular corners to the four balls. As hydraulic force is applied andthe balis cold-work the race wires, seats or crater-like tracks havingan arcuate crosssection of the nature shown in FIG. 2 are provided.Because transforming the corner of a rectangular bar to a track ofarcuate cross-section involves greater cold-working of the wire racesand more metalmovement to produce an arcuate seat of given contactlength, the process of the present invention provides harder and moredurable races, and thereby improves bearing life.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained, and,since certain changes may be made in carrying out the above methodwithout departing from the scope of the invention, it is intended thatall matter contained in the above descriptions or shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A method of manufacturing a wire-race ball hearing, comprising thesteps of: spacing a plurality of hard ened wire split rings in aselected configuration about a plurality of hardened balls to engagesaid balls; rotating said hardened wire rings and simultaneouslyapplying a load force to said wire rings, said load force being greaterthan the force to which the ball bearing is intended to be subjectedafter manufacture, thereby cold-working portions of said wire rings toprovide indented tracks of arcuate cross-section; and mounting saiddeformed wire rings on inner and outer supporting members in the sameconfiguration with respect to further hardened balls having the samediameter as said balls of said plurality.

2. The method according to claim 1 in which said hardened wire splitrings have corners along their lengths and the step of spacing saidrings causes said corners of said rings to initially engage said balls.

3. The method of claim 1 in which said load force applied to said ballsis applied parallel to the axis about which said wire rings are rotatedWhile said load force is being applied.

4. The method of claim 1 in which said plurality of hardened ballsincludes at least four balls spaced around said wire rings.

5. The method according to claim 2 in which said corners of said ringsare cold-worked to provide said indented tracks.

References Cited UNITED STATES PATENTS 2,399,847 5/ 1946 Bauersfield308216 2,917,351 12/1959 Franke et al 29148.4 X 3,081,135 3/1963 Olson308195 3,099,073 7/1963 Olson 29-1484 3,332,728 7/1967 Gibson 308-193THOMAS H. EAGER, Primary Examiner.

